DataTypeNotSupportedError: Data type "Object" is not supported by "postgres" database

Issue type:

[ ] question [x] bug report [ ] feature request [ ] documentation issue

Database system/driver:

[ ] cordova [ ] mongodb [ ] mssql [ ] mysql / mariadb [ ] oracle [x] postgres [ ] sqlite [ ] sqljs [ ] websql

TypeORM version:

[ ] latest [x] @next [ ] 0.x.x (or put your version here)

Steps to reproduce or a small repository showing the problem:

@Column({nullable: true})
  receivedAt: Date;

The previous code used to work, after upgrading to latest @next snapshot now I get the following error:

(node:2899) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): DataTypeNotSupportedError: Data type "Object" in "Recipient.receivedAt" is not supported by "postgres" database.

How am I supposed to specify a generic date type which will work with most dbs? @CreateDateColumn is not an option because it will have to be initialized with a null value and updated with a date later on.